4.00" stroke small block crank

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Old September 22nd, 2016, 09:53 AM
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4.00" stroke small block crank

Gauging interest on an American made 4340 4.00" stroke small block crank.
It would most likely be internally balanced, a 2.100 Rod journal and in the neighborhood of a $1000-$1200 price range. Let me know your thoughts. Thanks!
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Old September 22nd, 2016, 10:25 AM
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That sounds great and reasonably priced for a quality crank. Would custom pistons be necessary or would any existing off the shelf piston and sbc rod work?
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Old September 22nd, 2016, 02:34 PM
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With a 6.125 rod there are a host of 4.125 bore off the shelf pistons available from manufacturers like JE, SRP, and Mahle to name a few. Lots of choices.
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Old September 22nd, 2016, 09:56 PM
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Looks like BBO heads or even better Edelbrock or Procomps without would provide 10 to 1+ compression with a 10cc dish piston. No more milling new aluminum heads to get decent compression on a SBO.
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Old September 22nd, 2016, 10:02 PM
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10:1 compression aluminum headed 428 cid engine would be awesome.
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Old September 23rd, 2016, 05:48 AM
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2.5" mains or?
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Old September 23rd, 2016, 06:12 AM
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I would hope so since spacers in the DX block has been proven to be reliable for big power. Plus less friction with the smaller mains.
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Old September 23rd, 2016, 08:59 AM
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Originally Posted by Fun71
10:1 compression aluminum headed 428 cid engine would be awesome.
x2 I'd be interested.
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Old September 23rd, 2016, 10:33 AM
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Hey cutlass I thought bout stroking mine thought it wouldn't be worth it for my turbo build I'm already 4.125 bore
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Old September 23rd, 2016, 02:55 PM
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Originally Posted by turbodolds
Hey cutlass I thought bout stroking mine thought it wouldn't be worth it for my turbo build I'm already 4.125 bore

There's no replacement for displacement, even with a turbo.
Yes 2.500" mains.
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Old September 24th, 2016, 12:38 AM
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I'm definitely interested in this. Any ideas about time frame?
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Old September 24th, 2016, 05:15 AM
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We're looking for an existing forging that we can modify to work with the Olds bore centers and bearing placement. For right now it's moving forward. But if we can't find something existing then it'll be a dead issue. Raw forgings are just too much money.
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Old September 24th, 2016, 07:57 AM
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Mark, what compression height is needed for a 4" stroke? I know it depends on rod length. I want to use my current 403 stroker pistons set up for a 6" rod and 3.5" stroke. I come up with a 1.58" current compression height. Looks like with a 5.7 rod would put them .050" in the hole. I would deck .020-.030" and run the Cometic .027" head gasket. I like the sound of 484 ci over 424 ci any day. Count me in and would come up with a deposit if I had to after I pay for the rest of that custom cam. I will be $500 a month richer come January.
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Old September 24th, 2016, 11:21 AM
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Hold your horses Christian!😀
I wish we were that close but we're not, probably 6 months minimum, and that's if everything goes to plan.
You'll need to vase your compression height off the rods as mentioned. But be careful about using a shorter Rod just to be able to use your pistons. The shorter the rod the harder it is on cyl walls, especially on a 403.
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Old September 24th, 2016, 03:05 PM
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Good point Mark on the cylinder walls but may risk it. At the same time 484 ci would mean huge torque. I wonder how long a stock TH350 and a 7.5" with a girdle cover and better spider gears would last? 6 months is no problem, this would be a track only car, my 88 CSC, striping the interior etc. Procomp heads would be needed, big valve #6 heads would be a no go, choke it to death. My current 3.5" stroked 330 crank needs balanced and would go in the 350 block eventually.
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